Here, the values of thecollege_codecolumn must be unique. SQL UNIQUE Constraint Syntax The syntax of the SQLUNIQUEconstraint is: CREATETABLEtable_name ( column_name data_typeUNIQUE); Here, table_nameis the name
The syntax of the SQLCHECKconstraint is: CREATETABLEtable_name ( column_name data_typeCHECK(condition) ); Here, table_nameis the name of the table to be created column_nameis the name of the column where the constraint is to be implemented data_typeis the data type of the column such ...
1. No Action: This is the default behaviour. No Action specifies that if an attempt is made to delete or update a row with a key referenced by foreign keys in existing rows in other tables, an error is raised and the DELETE or UPDATE is rolled back. 2. Cascade: Specifies that if an...
Databricks SQL Databricks Runtime 將資訊主鍵或資訊外鍵新增為CREATE TABLE或CREATE MATERIALIZED VIEW語句的一部分。 若要將檢查條件約束新增至 Delta Lake 數據表,請在建立數據表之後使用ALTER TABLE。 語法 使用table_constraint子句來定義跨越多個數據行的條件約束,或將語法與數據行定義分開。
To allow naming of a CHECK constraint, and for defining a CHECK constraint on multiple columns, use the following SQL syntax:MySQL / SQL Server / Oracle / MS Access:ALTER TABLE Persons ADD CONSTRAINT CHK_PersonAge CHECK (Age>=18 AND City='Sandnes'); ...
To create aUNIQUEconstraint on the "ID" column when the table is already created, use the following SQL: MySQL / SQL Server / Oracle / MS Access: ALTERTABLEPersons ADDUNIQUE(ID); To name aUNIQUEconstraint, and to define aUNIQUEconstraint on multiple columns, use the following SQL syntax:...
Transact-SQL syntax conventions Syntax syntaxsqlคัดลอก [CONSTRAINTconstraint_name] { [NULL|NOTNULL] {PRIMARYKEY|UNIQUE} [CLUSTERED|NONCLUSTERED] [WITHFILLFACTOR= fillfactor ] [WITH(index_option[, ...n ] ) ] [ON{partition_scheme_name(partition_column_name) | filegroup |"default...
我想运行一个查询来创建一个表用户,但是在执行查询时,我得到了一个错误:Started executing query at Line 1 Msg 102, Level 15, State 1, Line 1 Incorrect syntax near '‘。总执行时间:00:00:00.031 CREATE TABLE `users` ( `login` varchar(30) NOT NULL, `password` varchar(32) NOT NULL ...
When defining referential integrity from a SQL DDL statement it is necessary to name a constraint when using the CONSTRAINT keyword. If a constraint name is not desired, then do not use the CONSTRAINT keyword. An example of this error would be: CREATE TABLE Customers (CLstNm TEXT(50), CFrs...
Syntax Arguments Remarks Examples Related content Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance SQL database in Microsoft Fabric Specifies the properties of a PRIMARY KEY, FOREIGN KEY, UNIQUE, or CHECK constraint that is part of a new column definition added to a table by...